The Patriot missile was not designed to shoot down other missiles, it was designed to shoot down airplanes. Something that it did very well by shooting down a British fighter. The Patriot is a very smart system, in fact, it will operate on it’s own. You have to manually tell it NOT to shoot. The error with the British fighter was that the computer saw a jet exiting hostile airspace without a ‘friendly’ transponder signal. The missile operators were in a bunker due to an attack, or suspected attack, and did not stop the Patriot from firing.

There is a myth that the Patriot got it’s Anti-Missile tag when a smart operator realized that you could program the computer to recognize a ballistic curve of a missile, and target it.

One more factoid; The Patriot always looks like it misses the target, partly because only a very high speed camera can film it, but it’s also because it does. It’s never intended to strike a target from the front. It closes with the target, turns and strikes from behind. The computer can not compute changing range rates accurately on a frontal strike. But this is an easy thing when approaching from behind.